The present invention relates to a torsionally elastic coupling wherein two halves of the coupling are twistable with respect to one another through at least one spring link to transmit torque, between the halves and through the coupling in series with said spring link. At least one motion-changing link connecting the two halves to each other and to the spring link is capable of changing rotational movement to translational movement, or vice versa, to transmit force through at least one bearing plate that radially on the outside rests on at least one spring link and that radially on the inside is supported in a force-locking manner in connection with a first of the two halves of the coupling. The motion-changing link, directly or through at least one translating coupling link, is coupled in such a way that the bearing plate at the time of twisting of the second half of the coupling relative to the first half starting from the zero position, is acted upon at least essentially radially to tighten or relax the spring link. The second half of the coupling rotates and is firmly connected with the motion-changing link.
A coupling of this type is part of the state of the art according to European Patent Application EP No. 83 103 977.1 belonging to the same assignee that has not been previously published. In order to avoid repetition, it is stated here explicitly that this European patent application, as a whole, is part of the scope of the original disclosure of the present application.
The characteristic torque twisting angle curve of the coupling of the state of the art is characterized in that, corresponding to the increasing restoring force, it progressively rises more or less softly with the increasing deflection of the spring link when the applied effort, i.e., the torque, is increased. This progressive rise, when elastomer spring assemblies are used as the spring link, increases even more with an increasing torque. In other words, in the range of higher and maximum on-load torques, only a small additional twisting angle is available for an indicated increase in load when the overall twisting angle of the torsionally elastic coupling is large. Therefore, impacts of load changes are absorbed only moderately, especially in the critical range of high torques. Thus, with a torsionally elastic coupling designed for a special range according to the state of the art, in the mean available twisting angle range and torque range a load change of, for example, 10 Nm can be absorbed by a twisting of the torsionally elastic coupling by 10.degree., but at higher values of torque the same amount of load change of 10 Nm would be absorbed over a twisting angle of, for example, only 2.degree. or 3.degree.. This is called a hardening of the characteristic torque/twisting angle curve. Such a hardening of the characteristic torque/twisting angle curve is undesirable, especially in the range of high torques, since any system, such as the drive line of a motor vehicle, in the range of relatively high torques is very stressed anyhow. At higher values of input torque, therefore, the impact of load changes should preferably be cushioned especially well.